Circuit breaker tank



Nov. 8, 1960 H. H. MITCHELL.

CIRCUIT BREAKER TANK 2 Sheets-Sheet 1 Filed Deo. 24, 1958 LJ L3 Nov. v8, 1960 H. H. MrrcHELL 2,959,655

CIRCUIT BREAKER TANK Filed Dec. 24. 1958 FIZ- c2257.

INVENTOR. A64/Fa H. #U70/u BY MM@ n ,4a/9%@ United States Patent C) CIRCUIT BREAKER TANK Harold H. Mitchell, La Canada, Calif., assigner to IT-E Circuit Breaker Company, Philadelphia, Pa., a corporation` of Pennsylvania Filed Dec. 24, 1958, Ser. No. 782,824

17 Claims. (Cl. 20G-150).

The instant invention relates generally to oil circuit breakers and more particularly to an improvement in the tank construction thereof which enables given performance figures to be maintained with a reducedA amount of oil.

In oil circuit breakers the oil serves two primary purposes, first, it acts as a high dielectric' medium interposed between the energized parts of the circuit breaker and the grounded portion of the structure and, secondly, during interruption the oil acts as a cooling medium and is a means for flushing the products of arcing fromy the gap between the parting contacts.

Oil circuit breakers of theV prior art have been constructed with the contacts disposed within` a cylindricalV tank. Beacuse of the overall configuration of the internal parts (ie. entrance bushings, interrupting elements, and cross-head) an extreme thickness of oil is inherently present between the central portion of the internal parts and the tank, with this` thickness being measured in a plane extending perpendicular to the plane vof the entrance bushings. This extreme thickness or" oil at the central portion serves no usefulV purpose, but merely adds to the overall weight of the circuit breaker unit and also results in a more bulky unit.

The oil circuit breaker of the instant invention cornprises a tank construction which is based upon simple geometric elements that are readily fabricated and which ywill obviate the use of extraneous oil. Briey, the tank :of the instant invention comprises a lower pan or bowllike section and two intersecting column sections extendling upwardly from the bowl section with the axes of `the column sections intersecting at a point below the lower ends of the column sections. The studs to which :the stationary contacts of the circuit breaker are mounted extend through the column sections and are positioned coaxially therewith. The column sections are of circular Icross-section so that the equi-potential lines between each ;stud and its associated column are circular in form.

In the optimum design of a tank constructed in, acicordance with the instant invention, the shape is predicated upon obtaining as closely as possible uniform po- 'tential gradients from all internal parts to the grounded tank. This may be achieved by forming the column sections of frustums of a cone with thev base positioned at the lower end of the column. The columns are then ljoined at their lower ends by a pan whose. cross-section is semi-circular in a plane through its major axis and is somewhat elliptical in a plane through its minor axis.

Accordingly, a primary object of the instant invention is to provide a novel, compact, low weight oil circuitv breaker.

Another object is to provide an oil circuit breaker in `which there are substantially uniform potential gradients Yfrom all of the internal structure to the grounded tank.

A further object is to provide an oil circuit breaker in which the tank includes a pair of intersecting columns ICC whose longitudinal axes intersect at a point below theends of the columns.

A still further object is to provide an oil circuit breaker in which the tank columns are in the form of frustums of cones with the bases thereof being positioned at the lower ends of the columns.

These as well as other objects of the instant invention shall become readily apparent after reading the following descriptionV of the accompanying drawings in which:

Figure 1 is a side elevation of a three phase oil circuit breaker constructed in accordance with the teachings of the instant invention.

Figure 2 is an end view` of a single phase of the circuit breaker of Figure 1 looking in the direction of the arrows 2 2'.

Figure 3 is a longitudinal cross-section of a single phase of the circuit breaker taken through line 3 3 of Figure l looking in the direction of arrows 3 3;

Figures 4 and 5 are cross-sections taken through lines 4 4 and 5 5, respectively, of Figure 2. looking in the direction of the arrows.

Figure 6 is a cross-section taken through line 6 6 of Figure 3 lookingin theV direction of the arrows 6 6.

Figure 7 is a side elevation of a second embodiment of an oil circuit breaker constructed in accordance with the teachings of the instant invention and includes two intersecting columns shaped as frustums of cones.

Figure 8 is an end View of a single phase of the circuit breaker of Figure 7 looking in the direction of the arrows 8 8.

Figure 9 is a longitudinal cross-section of a single phase of the circuit breaker of Figure 7 taken through line 9 9 looking in the direction of the arrows 9 9.

Figures 10 and 1l are cross-sections taken through lines N l and Il ll, respectively, of Figure 8 looking in the direction of the arrows.

Now referring more particularly to Figures 1-6, three phase circuit breaker 1S comprises three identical single phase circuit breakers 16, 17, 18 ganged together for simultaneous operation by means of operating mechanisrn 19 which is of a type well known in the art, such as the mechanism illustrated in copending application (PC-13) Serialy No. 767,340, led October 15, 1958, with James R. McCloud as inventor, entitled Pole Unit Mechanism, and assigned to. the assignee of the instant invention.

Circuit breaker 16 comprises a tank 17 adapted to be filled with oil (not shown). A pair of entrance bushings 13' are entered into tank 17l with the flanges 19 of bushings 18' being mechanically secured to tank 17. Currentk studs 20 extend axially through bushings 18 and, at their lower ends, studs Ztl are each provided withV an interrupter unit 21 which comprises a stationary contact and asso-V ciated arc quenching means well known to the oil circuitY breaker art.

Movable contacts 22, which are engageable with the stationary contacts (not shown) of interrupters 21, are positioned at opposite sides of cross-headV 23. A reciprocable rod 24 is secured to cross-arm 23 atits mid-point with the upper end of rod 24 being engageable. by an extension of operating mechanism 19 to cause operation of cross-head 23 from the closed circuit position, indicated by the solid lines of Figure 3, to the open circuit position, indicated in phantom in Figure 3.

Tank 17 comprises two cylindrical column sections 25, 26 which extend upwardly from dish or pan 27. Column sections 25, 26 are arranged in intersecting relationship so that their longitudinal axes 28, 29, respectively, intersect; at a point below the lower ends of columns 25, 26.

Entrance bushings 18, are provided with grounded portions 30 which, extend below the respective flanges. 19

Patented Nov. 8, 1960 in order to have all of the potential gradient from the bottom of studs 20 to the lower extremities of grounded portions 30 under oil. Bushing type transformers 31 are mounted around the grounded portions 30 of entrance bushings 13. The cross-sections of entrance bushings 18 are rounded in planes taken perpendicular to the longitudinal axes 2S, 29 of column sections 25, 26, respectively. Therefore, the equi-potential lines will radiate in circular fashion from any portion of entrance bushings 18 below rounded portions't) in planes also perpendicular to axes 2S, 29 since the grounded tank 17 is disposed at an equal distance from the bushings 18 in any plane taken perpendicular to axes 28, 29.

The cross-head 23 is disposed within tank 17 below the point at which column sections 25, 26 intersect. As crosshead 23 approaches the fully opened position its potential approaches that of ground so that very little, if any, oil is required in the space between the cross-head in the fully opened position and the nearest grounded area which is the bottom of pan 27.

Pan 27, as illustrated, is comprised of two half sections of elliptical shape welded together along circular lips so as tto form a dish semi-circular in plane taken through its major axis 32 and somewhat elliptical in a plane through its minor axis 23 which is also the weld line.

By merely observing the cross-section of tank 17, illustrated in Figure 6, it is readily seen how a circuit breaker constructed in accordance with the instant invention requires considerably less oil within the tank than the typical cylindrical tank of the prior art. The saving of oil in the plane 6 6 (Figure 6) is illustrated by the cross-hatched areas 34, 35.

Now referring more particularly to Figures 7-11 wherein a second embodiment of the instant invention is illustrated. In this embodiment only the shape of the circuit breaker tank has been modified, with all other components remaining the same so that common reference numerals have been utilized to identify the same numbers in each of the figures.

Three phase circuit breaker `40 comprises three identical single phase circuit breakers 41, 42, 43 which are ganged together for simultaneous operations by means of operating mechanism 19. Circuit breaker tank 44 is comprised of two intersecting column sections 45, 46 each shaped as a frustum of a cone with the base positioned at the lower end thereof. The longitudinal axes 47, 48 of column sections 45, 46, respectively, intersect at a point below the ends of column sections 45, 46. A bowl-like pan 49, similar in shape to pan 27 hereinbefore described, is positioned at the lower ends of column sections 45, 46.

The utilization of frusto conical column sections 45, 46 produces an even more ideal combination than the utilization of cylindrical column sections 25, 26 inasmuch as the voltage to ground varies from zero at the bottom of the grounded portions 30 of bushings 18, to a maximum at the lower ends of current studs 20. The clearance between bushings 18 and the tank 44 can also vary from zero to the clearance for maximum voltage.

The utilization of frusto conically shaped column sections 44, 46 coincides closely with the desired sections, and in turn, uses the oil at approximately the same poten- 4tial gradient whether at the top, bottom or an intermediate position along the portions of bushings 13 entered into tank 44. It is to be noted, that in the embodiment of Figures 7-11 current transformers 31 are disposed above the upper ends of column sections 45, 46 in separate removable housings 50.

Thus, I have provided a novel construction for the tank of an oil circuit breaker which materially reduces the amount of oil required thereby effecting a substantial reduction in the weight of the circuit breaker as well as a saving in the cost of oil. This construction is also advantageous in that the tank is readily fabricated.

Although I have here described PIQQIIQ Gmbodmnt of my novel invention, many variations and modifications will now be apparent to those skilled in the art, and I therefore prefer to be limited, not by the specific disclosure herein, but only by the appending claims.

I claim:

l. A tank for an oil circuit breaker comprising a bottom bowl section and extending upwardly therefrom a pair of intersecting hollow column sections; said column sections being positioned with the longitudinal axes thereof intersecting at a point below the lower ends of said columns.

2. A tank for an oil circuit breaker comprising a bottom bowl section and extending upwardly therefrom a pair of intersecting hollow column sections; said column sections being positioned with the longitudinal axes thereof intersecting at a point below the lower ends of said columns; said bowl section having a major and a minor axis positioned in a horizontal plane; said bowl section being of a generally elliptical cross-section in a vertical plane throughv said minor axis.

3. A tank for an oil circuit breaker comprising a bottom bowl section and extending upwardly therefrom -a pair of intersecting hollow column sections; said column sections being positioned with the longitudinal axes thereof intersecting at a point below the lower ends of said columns; said bowl section having a major and a minor axis positioned in a horizontal plane; said bowl section being of a generally elliptical cross-section in a vertical plane through said minor axis; said bowl section being of a generally circular arc cross-section in a vertical plane through said major axis.

4. A tank for an oil circuit breaker comprising a bottom bowl section and extending upwardly therefrom a pair of intersecting hollow column sections; said column sections being positioned with the longitudinal axes thereof intersecting at a point below the lower ends of said columns; each of said column sections being circular in cross-section through a plane perpendicular to the longitudinal axis thereof.

5. A tank for an oil circuit breaker comprising a bottom bowl section and extending upwardly therefrom a pair of intersecting hollow column sections; said column sections being positioned with the longitudinal axes thereof intersecting at a point below the lower ends of said columns; each of said column sections being circular in cross-section Ithrough a plane perpendicular to the longitudinal -axis thereof; each of said columns being in the shape of frustum of a cone having its base at the lower end thereof.

6. A tank for an oil circuit breaker comprising a bottom bowl section and extending upwardly therefrom a pair of intersecting hollow column sections; said column sections being positioned with the longitudinal axes thereof intersecting at a point below the lower ends of said columns; each of said column sections being circular in cross-section through a plane perpendicular to `the longitudinal axis thereof; each of said columns being in the shape of a frustum of a cone having its base at the lower end thereof; said bowl section being of a generally elliptical cross-section in a vertical plane through said minor axis; said bowl section being of a generally circular arc cross-section in a vertical plane through said major axis.

7. A circuit breaker comprising a tank and disposed within said tank a pair of spaced stationary contacts and a bridging member mounted to a vertically reciprocable operating rod transverse to the longitudinal axis thereof; said bridging member bridging the gap between said stationary contacts when said rod is in a raised position; said gap being open when said rod is in a lowered position; said contacts and said bridging member being surrounded by a dielectric fluid confined Within said tank; said tank being comprised of a pair of intersecting hollow column sections; Said column sections being generally vertically extending and being positioned with the longitudinal axes the'reor`` intersecting at a pointbelow the lowerv ends' of said columns.

8. A circuit breaker comprising a tank and disposed withinsaid tank a pair of spaced stationary contactsy and a bridging member mounted to a vertically reciprocable operating rod transverse to the longitudinal axis thereof; said bridging member bridging the gap between said stationary contacts when said rod is in a raised position; said gap being open when said rod is in a lowered position; said contacts and said bridging member being surrounded by a dielectric iluid confined within said tank; said tank being comprised of a pair of intersecting hollow column sections; said column sections being generally vertically extending and being positioned with the longitudinal axes thereof intersecting at a point below the lower ends of said columns; an end member capping the upper end of each of said column sections; an insulating bushing for each of said end members secured thereto and extending through openings therein; a conducting study for each of said column sections extending through said bushing and arranged coaxially with its associated coiumn; said stationary contacts being mounted to the lower ends of said studs withv the upper ends of said studs extending beyond the upper ends of said column sections.

9. A circuit breaker comprising a tank and disposed within said tank a pair of spaced stationary contacts and a bridging member mounted to a vertically reciprocable operating rod transverse to the longitudinal axis thereof; said bridging member bridging the gap between said stationary contacts when said rod is in a raised position; said gap being open when said rod is in a lowered position; said contacts and said bridging member being surrounded by a dielectric fluid confined Within said tank; said tank being comprised of a pair of intersecting hollow column sections; said column sections being generally vertically extending and being positioned with the longitudinal axes thereof intersecting at a point below the lower ends of said columns; an end member capping the upper end of each of said column sections; an insulating bushing for each of said end members secured thereto and extending through openings therein; a conducting stud for each of said column sections extending through said bushings and arranged coaxially with its associated column; said stationary contacts being mounted to the lower ends of said studs with the upper ends of said studs extending beyond the upper ends of said column sections;

said tank including a bowl section-secured to said column sections at their lower ends; said bridging member being disposed within said bowl section when said rod is in said lowered position.

l0. A circuit breaker comprising a tank and disposed within said tank a pair of spaced stationary contacts and a bridging member mounted to a vertically reciprocable operating rod transverse to the longitudinal axis thereof; said bridging member bridging the gap between' said stationary contacts when said rod is in a raised position; said gap being open when said rod is in a lowered position; said contacts and said bridging member being surrounded by a dielectric lluid confined within said tank; said tank being comprised of a pair of intersecting hollow column sections; said column sections being generally vertically extending and being positioned with the longitudinal axes thereof intersecting at a point below the lower ends of said columns; `an end member capping the upper end of each of said column sections; an insulating bushing for each of said end members secured thereto and extending through openings therein; a conducting stud for each of said column sections extending through said bushings and arranged coaxially with its associated column; said stationary contacts being mounted to the lower ends of said studs with the upper ends of said studs extending beyond the upper ends of said column sections; said tank including a bowl section secured to said column sections at their lower ends; said bridging member being disposed within said bowl section when said rod is in said lowered posi- 'aeeagessfr tion; eaclrof said column sections being circular in crosssectiontllrough a plane perpendicular to the longitudinal axis thereof.

111. A circuit breaker comprising a tankk and disposed within said tank a, pair of spaced stationary contacts and a bridging; member mounted to a vertically reciprocable operating rod transverse to the longitudinal axis thereof; said bridging member bridging the gap between said stationary contacts when said rod is in a raised position; said gap being open when said rod is in a lowered position; said contacts and said bridging member being surrounded by a dielectric fluid coniined within said tank; saidftank being comprised of a pair of intersecting hollow column sections; said column sections being generally vertically extending and being position with the longitudinal axes thereof intersecting at a point below the lower ends of said columns; an end member capping the upper end of. eachof said column sections; an insulating bushing for each of said end members secured thereto and extending through openings therein; a conducting, stud for each of said column sections extending throughv said bushings and arranged coaxially with its associated column; said stationary contacts being mounted to the lower ends of said studs with the upper ends of said studs extending beyond the upper ends of said column sections; said tank including a bowl section secured to said column sections. at their lower ends; said bridging member being disposed within said bowl section when said rod is in said lowered position; each of said column sections being circular in cross-section through a plane perpendicular to the longitudinal axis thereof; each of said columns being inthe-shape of a frustum of a cone having its base at the lower end thereof.

12. A circuit breaker comprising a tank and disposed within said tank a pair of spaced stationary contacts and a bridging member mounted to a vertically reciprocable operating. rod transverse to the longitudinal axis thereof;

erally vertically extending and being positioned with the longitudinal axesr thereof intersecting at a point below the lower endso said columns; an end member capping the upper end of each of said column sections; an insulating bushing for each of said end members secured thereto and extending through openings therein; a conductingstud for each-of said column sections extending through said bushingsand arranged coaxially with its associatedV column; said. stationary contacts being mounted to the lower ends of said studs with the upper ends of said studs extending beyond the upper ends of saidcolumn sections; said tank including a bowl section secured to said column sections at their lower ends; said bridging member being disposed within said bowl section when said rod is in said lowered position; said bowl section having a major and a minor axis positioned in a horizontal plane; said bowl section being of a generally elliptical cross-section in a vertical plane through said minor axis.

13. A circuit breaker comprising a tank and disposed within said tank a pair of spaced stationary contacts and a bridging member mounted to a vertically reciprocable operating rod transverse to the longitudinal axis thereof; said bridging member bridging the gap between said stationary contacts when said rod is in a raised position; said gap being open when said rod is in a lowered position; said contacts and said bridging member being surrounded by a dielectric uid conned within said tank; said tank being comprised of a pair of intersecting hollow column sections; said column sections being generally vertically extending and being positioned with the longitudinal axes thereof intersecting at a point below the lower ends of said columns; an end member capping the upper end of each of said column sections; an insulating bushing for each of said end members secured thereto and extending through openings therein; a conducting stud for each of said column sections extending through said bushings and arranged coaxially with its associated column; said stationary contacts being mounted to the lower ends of said studs with the upper ends of said studs extending beyond the upper ends of said column sections; said tank including a bowl section secured to said column sections at their lower ends; said bridging member being disposed within said bowl section when said rod is in said lowered position; each of said column sections being circular in cross-section through a plane perpendicular to the longitudinal axis thereof; said bowl section having a major and a minor axis positioned in a horizontal plane; said bowl section being of a generally elliptical cross-section is a vertical plane through said minor axis; said bowl section being of a generally circular arc cross-section in a vertical plane through said major axis.

14. A circuit breaker comprising a tank and disposed within said tank a pair of spaced stationary contacts and a bridging member mounted to a vertically reciprocable operating rod transverse to the longitudinal axis thereof; said bridging member bridging the gap between said stationary contacts when said rod is in a raised position; said gap being open when said rod is in a lowered position; said contacts and said bridging member being surrounded by a dielectric fluid confined within said tank; said tank being comprised of a pair of intersecting hollow column sections; said column sections being generally vertically extending and being positioned with the longitudinal axes thereof intersecting at a point below the lower ends of said columns; an end member capping the upper end of each of said column sections; an insulating bushing for each of said end members secured thereto and extending through openings therein; a conducting stud for each of said column sections extending through said bushings and arranged coaxially with its associated column; said stationary contacts being mounted to the lower ends of said studs with the upper ends of said studs extending beyond the upper ends of said column sections; said tank including a bowl section secured to said column sections at their lower ends; said bridging member being disposed within said bowl section when said rod is in said lowered position; each of said column sections being circular in cross-section through a plane perpendicular to the longitudinal axis thereof; said bowl section having a major and a minor axis positioned in a horizontal plane; said bowl section being of a generally elliptical cross-section is a vertical plane through said minor axis; said bowl section being of a generally circular arc cross-section in a vertical plane through said major axis; each of said bushings having a first portion thereof disposed within its said associated column section; said first portions being partially covered with a conducting material at the same electrical potential as said tank; said tank sections and the circuit breaker components disposed within said tank being proportioned and relatively positioned whereby said dielectric fluid is subjected to subs-tantially the same potential gradient throughout.

l5. A tank for an oil circuit breaker comprising a bottom bowl section and extending upwardly therefrom a pair of intersecting hollow column sections; said column sections being positioned with the longitudinal axes thereof intersecting at a point below the lower ends of said columns; said tank `defining a volume adapted to be occupied by a dielectric fluid; said column sections defining a substantial portion of said volume in comparison to the portion of said volume defined by said bowl section.

16. A tank for an yoil circuit breaker comprising a bottom bowl section and extending upwardly therefrom a pair of intersecting hollow column sections; said column sections being positioned with the longitudinal axes thereof intersecting at a point below the lower ends of said columns; said bowl section having a major and a minor axis positioned in a horizontal plane; said bowl section being of a generally elliptical cross-section in a vertical plane through said minor axis; said bowl section having a maximum dimension taken along said major axis in a horizontal plane; said column sections appearing as continuations of said bowl section extending upward from the plane in which said maximum dimension is taken.

l7. A tank for an =oi=l circuit breaker comprising a bottom bowl section and extending upwardly therefrom a pair of intersecting hollow column sections; said column sections being positioned with the longitudinal axes thereof intersect-ing at a point below the lower ends of said columns; said bowl section having a major and a minor axis positioned in a horizontal plane; said bowl section. being of a generally elliptical cross-section in a vertical plane through said minor axis; said bowl section having a maximum dimension taken along said major axis in a horizontal plane; said column sections appearing as con-v tinuations of said bowl section extending upward from the plane in which said maximum dimension is taken; said tank deiining a volume adapted to be occupied by a dielectric fluid; said column sections dening a substantial portion of said volume in comparison to the portion of said volume dened by said bowl sect-ion.

References Cited in the tile of this patent UNITED STATES PATENTS 2,835,769 Milne et al. May 20, 1958 FOREIGN PATENTS 626,198 Great Britain July ll, 1949 

